NK cells stimulated by hapten or various viruses return to the liver in a CXCR6-dependent manner and stay there for several months, which may indicate the importance of CXCR6+ NK cells in HCC.87,88 Interestingly, in a recent study of diethylnitrosamine-induced liver cancer, CXCR6 deficiency reduced intrahepatic numbers of invariant NKT, CD4+, and CD8+ T cells. This evidence concerns the gene CD4 and hepatocellular carcinoma.